Artificial horizon for optical instruments



ARTIFICIAL HoRIzoN Fon OPTICAL INSTRUMENTS Filed Ju1y11, 1942 2sheds-'sheet 1 /Z Im'wllor liv 0nd gwn. Attori/:fusi

Dec. 7, 1943. Q ALTENBERG 2,335,893

ARTIFICIAL HORIZON FOR OPTICAL INSTRUMENTS Filed July l1, 1942 2Sheets-Sheet 2 @im I "nl" Mln,

Inventor Oryz'ZZe ZJ AZZerz-ery maozm Patented Dec. 7, 1943 UNITEDSTATIYZSg PATENT v OFFICE YARTIFICIAL HomzoN Fon OPTICAL `INSTRUMENTS(.)rvillc L` Altenberg, Toledo, Ohio Application July 11, 1942, SerialNo. 450'I,589 l s claims. roi. ssa-2.2)

'The invention vrelates to an improved artificial horizon for opticalinstruments wherein a true level is required and for use for suoliVinstruments as engineers andarchitects levels, transits and sextants,and the primary object of the inven-I tion is to provide a more accurateand more usable device of this character which can be mounted on VtheAsextant or like instrument in a variety of positions; 7' v- Otherimportant objects and advantages of the invention will be apparent froma reading otthe following description taken in connection with theappendedV drawings, wherein for purposes of illustration a preferredembodiment ofthe invention is shown. f

In the drawingsY Figure lV is a general tional View taken through thearticialhorizon. FigureZ is a top plan View of Figure l. 1 Figure 3 is aright hand' end elevational view of Figurerl.

Figure 4 is a left l lhand yend.l elevational view oi Figure 1.

vertical; longitudinal secp Figure 5 is a side elevational viewzofa'sextant showing a permissivelmounting of the artificial horizonthereon.V

Figure 6 is aview similar to `Figure `5, partlyin diagrammatic form toillustrate another permissive mounting of the artiiicial horizon onasextant. l .i

.Figure 7 is a view similar to Figure 6. showing a still furtherpermissivemountingof the artificial horizon on a seXtant.

Referring in detail to the drawings, the artificial horizon which isgenerally designatedl by the .numeral 5 consists of a longitudinally andvertically elongated relatively narrowgenerally rectangular y housingconsisting of a block of plastic or other suitable material to favorlight weight and properly contain the mercury or other suitable levelfluid. The block is formed internally adjacent the ends thereof withsimilar andparallelrverf tical bores 6 and l. The upper ends of thebores are connected by a` horizontalvupper bore 8`, and o the lower endsof the vertical bores 6 and-'lare connected with the opposite ends of alower horizontal bore 9 which is substantially parallel to the upperhorizontal bore 8 and which is slightly larger in cross section anddiameter than the upper horizontal bore 8, the lower bore 9 constitutinga level fiuid reservoir having communication with both of the verticalbores 6 and 1.

As indicated in Figure 1 of the drawings, the left hand end of the firstbore 8 has an internally threaded extension I0 opening through the lefthand end` of the block, in which is threaded a plug IIon the outer endof which is a handle I2 enabling adjusting the plug inwardly oroutwardly to provide for raising or lowering the columns of the levelrfluid in the vertical'bores 6 and 1, the reservoir 9 and the lowerportions of the vertical bores 6 andA 1 being filled with the levelfluid I3, such as mercury or other suitable fluid. Glass or othertranslucent material inveritcal alignment above the upper ends of thevertical bores 6 and 'I as indicated in Figure 1 of the drawings, andother similar windowsl are placed in the endwallsof the block inhorizontal alignment with the upper bore 8, the purpose of the windowsbeing to provide suicient I light for viewing the menisci naturallyproduced on the upper ends of the columns of bores 6 and l. l

The block is cut through from a point adjacent its longitudinal middleto a point adjacent its left hand end; as indicated in Figure 1 of thedrawings to provide a relatively large void I6 within the block. Anothersmaller chamber or space I'I is formed entirely through the block inlongitudinally spaced relation to the chamber I6 and in longitudinallyspaced relation tothe adjacent end of the block, also to provide a voidsmaller than the -void provided by thefchamber I6.

Axially aligned pairs of tubular bushings I3 extend horizontally inabore I9 extending from the left hand end of the block into the chamberI6, with glass or other suitable translucent material windowsy 20 insetvin the facing ends of the bushings I8 flush with these ends and ush withthe walls of the vertical bore 6. should be relatively? transparent.Similar bushings I and glasses or other transparencies 'as lenses 25 aresimilarly arranged in the opposite end of the block with respect to thevertical bore fluid in the 1, the bushings I3 and the windows 20 beingaxially aligned with the dows 20. n l

The right hand end of the block is formed w1th a tapering extension 2|which is formed with a longitudinalbore 22 in theinner end portion ofwhichthe .rightk hand bushing IS' is inserted. -A collimation line isprovided by a wirev23 strung between the arms of a U-shapcd support 24mounted in the right hand end of the bore of the bushing I3', to occupya proper position in substantial coincidence with the axis of thespherical lenses 25 and 2E.

A horizontal bore 21 provided'in the block and opening into the chambersI6 and I1V as shown bushings I8 and winwindows M are placed The windows2E! in Figure l of the drawings has inserted therein a stationary tube28 which is internally threaded and into which is threaded the tube 29on the spherical lens mounting 39 which includes the threaded ring 3lholding the spherical lens 25 in place in the right hand end portion ofthe chamber I6. A similar mounting is provided for the positioning ofthe spherical lens 26 at the right hand end of the tapered extension 2l,the tube 28 of this lens mounting being inserted in the right hand endof the bore 22 of the said extension. The lenses 25 and 26 areadjustable toward and away from each other in an obvious andconventional manner.

When a proper amount of mercury or similar level fluid I3 is in thereservoir 9 the same will inverted images of the two menisci.

The described arrangement with the objects placed so that one is on the'optical axis and beyond the lenses and the object on the optical axisand located between the two lenses, provides for rays of light from therearward column vmenisci being acted on first by the rear lens 26 whichpresents them into the front lens 25 as an inverted image, and r-ays oflight from the forward column are acted on by the lens of the rise inthe vertical bores 6 and 1 to provide columns having menisci 32 at theirupper ends which are to be leveled with respect to the collimation line23 by tilting the artificial Vhorizon 5 either to the left or to theright from an other than absolutely level position. If in the levelposition of the block the menisci 32 of the columns rise above or aredepressed below the axis of the spherical lenses 25 and collimation line23, the columns may be raised or depressed by adjustment of the plug Ilin an obvious manner, to bring about coincidence.

Suitable adjusting means (not shown) rmay be easily devised to mount theartificial horizon 5 in different positions on and in differentlocations relative to a sextant such as below, on a level with, andbefore or behind the sextant telescope 34 as variously illustrated inFigures 5, 6 and 7 of the drawings, suitable mirror means being providedin each instance to transmit the image of the celestial body observedinto said telescope and into the artificial horizon 5, horizon glassesbeing utilized in each instance.

The spherical lenses 25 and 26 are so arranged that their foci andmanner of separation produce an erect image of one object viewed and aninverted image of another object viewed, when these objects are locatedat predetermined points with respect to the optical system comprisingsaid spherical lenses. The inversion of the image of one object and theerection of the image of the other object, are used in the presentdevice to provide an artiiicial horizon, consisting in this instance ofthe menisci of the two level iluid columns 32 which rise from a commonreservoir. Since the two menisci of the columns are Aconstantly at atrue level, with alignment of the menisci with the ,axes of the axiallyaligned spherical lenses 25 and 26, the images of the two menisci arepresented into the optical eld of a sextant telescope, apparently in thesame plane, with one image being erect and the other image inverted, andwith an aperture between the images of as small a size as the operatormay choose.

If the menisci of the fluid columns are depressed below the center ofthe optical system the images will appear to be greatly separated. Ifthe menisci are'positioned higher than the optical center of the lenssystem, then the image of only the front column is visible. If the blockbe forwardly down tilted with respect' to the horizontal, the forwardcolumn rises above the optiforward lens 25 only and are presented as anerect image of the menisci of the corresponding columns.

Although there is shown and described a preferred embodiment of theinvention it is to be denitely understood that it is not desired tolimitthe application of the invention thereto, exceptas may be requiredby the scope of the subjoined claims. f y

Having described the invention, what is claimed as new is: g

1. An artificial horizon for mounting on a sextant having a telescope,said artificial horizon comprising a support, a horizontal reservoir onsaid support, said reservoir being open at one end, an adjustable plugclosing the open end yof the reservoir, a pair 4of vertical `conduitsrising from and communicating with said reservoir, said verticalconduits being substantially spacedalong the reservoir, a horizontalconduit connecting the upper ends of said vertical bores, a suicientquantity of level fluid in said reservoir to provide columns rising insaid vertical conduits, said columns having menisci on their upper ends,axially aligned windows in said vertical conduits through which themenisci can be viewed with said support in a substantially levelhorizontal position, a first spherical lens mounted on said supportbetween said windows, a secondl spherical lens mounted on said supportat the outer side of one of said windows, said'spherical lenses beingaxially aligned, and a fixed collimation line mounted on said supportbetween the second lens and the adjacent window in axial alignment withthe lens, said plug being adjustable to'elevate or depress the menisciof the columns into coincidence with the collimation line,the supportbeing level.

2. An articial horizon according to claim l wherein said supportcomprises -a substantially solid block and said reservoir, verticalconduits, and said horizontal conduit consisting of bores formedinternally in the block.

3. The combination with a sextant having an horizon glass and atelescope, of an artificial horizon according to claim 1, wherein meansis provided for mounting the artificial horizon on a portion of thesextant in effective relation to said horizon glass and the telescope.

ORVILLE L. ALTENBERG.

